import React, { useState, useEffect } from 'react'
import {
  initiateLogin,
  initiateLogout,
  getCurrentUser,
  recommend,
  feedback,
  stats,
  getUsers,
  getContents,
} from './api'

export default function App() {
  const [authUser, setAuthUser] = useState(null)
  const [authChecked, setAuthChecked] = useState(false)
  const [ssoEnabled, setSsoEnabled] = useState(false)
  const [userId, setUserId] = useState('')
  const [contentId, setContentId] = useState('')
  const [algorithm, setAlgorithm] = useState('linucb')
  const [users, setUsers] = useState([])
  const [contents, setContents] = useState([])
  const [result, setResult] = useState(null)
  const [impressionId, setImpressionId] = useState(null)
  const [statsData, setStatsData] = useState(null)
  const [statusMsg, setStatusMsg] = useState('')

  async function refreshSession() {
    setStatusMsg('Checking authentication...')
    try {
      const auth = await getCurrentUser()
      setAuthUser(auth.user)
      setSsoEnabled(auth.sso_enabled)
      if (auth.user) {
        await loadLists()
      }
      setStatusMsg('')
    } catch (e) {
      setStatusMsg('Unable to verify authentication: ' + (e.message || e))
    } finally {
      setAuthChecked(true)
    }
  }

  async function loadLists() {
    try {
      const [u, c] = await Promise.all([getUsers(), getContents()])
      setUsers(u || [])
      setContents(c || [])
      if (u?.length && !userId) setUserId(u[0].user_id)
      if (c?.length && !contentId) setContentId(c[0].content_id)
    } catch (e) {
      setStatusMsg('Failed to load users or contents: ' + (e.message || e))
    }
  }

  async function handleRecommend() {
    setStatusMsg('Requesting recommendation...')
    try {
      const res = await recommend(userId, contentId, algorithm)
      setResult(res)
      setImpressionId(res.impression_id)
      setStatsData(null)
      setStatusMsg(`Recommendation delivered in ${Math.round(res.latency_ms)} ms`)
    } catch (e) {
      setStatusMsg('Error: ' + (e.message || e))
    }
  }

  async function handleFeedback(reward = 1.0) {
    if (!impressionId) {
      setStatusMsg('No recommendation available for feedback')
      return
    }
    setStatusMsg('Sending feedback...')
    try {
      await feedback(impressionId, reward)
      setStatusMsg('Feedback recorded successfully')
    } catch (e) {
      setStatusMsg('Error: ' + (e.message || e))
    }
  }

  async function handleStats() {
    setStatusMsg('Loading production stats...')
    try {
      const s = await stats()
      setStatsData(s)
      setStatusMsg('Stats loaded')
    } catch (e) {
      setStatusMsg('Error: ' + (e.message || e))
    }
  }

  useEffect(() => {
    refreshSession()
  }, [])

  const isReady = authChecked && (!!authUser || !authUser)

  return (
    <div className="container">
      <header className="topbar">
        <div>
          <p className="eyebrow">Artwork Bandit</p>
          <h1>Recommendation Studio</h1>
          <p className="subtitle">A modern SSO dashboard for artwork recommendation, feedback, and performance insights.</p>
        </div>
        <div className="profile-bar">
          {authChecked ? (
            authUser ? (
              <>
                <div className="profile-info">
                  <span>{authUser.name}</span>
                  <small>{authUser.email}</small>
                </div>
                <button className="secondary" onClick={initiateLogout}>Sign out</button>
              </>
            ) : ssoEnabled ? (
              <button className="primary" onClick={initiateLogin}>Sign in with SSO</button>
            ) : (
              <div className="profile-info">
                <span>SSO is not configured</span>
                <small>Please set SSO environment variables to enable login.</small>
              </div>
            )
          ) : (
            <span>Checking login...</span>
          )}
        </div>
      </header>

      {!authUser ? (
        <main className="hero-card">
          <div>
            <h2>Secure access with SSO</h2>
            <p>Sign in to access the artwork recommendation engine, track model performance, and share feedback securely.</p>
            <button className="primary" onClick={initiateLogin} disabled={!ssoEnabled}>
              {ssoEnabled ? 'Start with SSO' : 'SSO not configured'}
            </button>
          </div>
          <div className="hero-aside">
            <p>Configured backend SSO keeps your recommendation experiments protected while preserving the same fast feedback loop.</p>
            {!ssoEnabled && <p className="empty-state">Set <code>SSO_DISCOVERY_URL</code>, <code>SSO_CLIENT_ID</code>, and <code>SSO_CLIENT_SECRET</code> to enable login.</p>}
          </div>
        </main>
      ) : (
        <main>
          <section className="dashboard-grid">
            <section className="panel controls-panel">
              <h2>Recommendation controls</h2>
              <label>
                Dataset user
                <select value={userId} onChange={(e) => setUserId(e.target.value)}>
                  {users.map((u) => (
                    <option key={u.user_id} value={u.user_id}>{u.user_id}{u.mood ? ` — ${u.mood}` : ''}</option>
                  ))}
                </select>
              </label>

              <label>
                Content topic
                <select value={contentId} onChange={(e) => setContentId(e.target.value)}>
                  {contents.map((c) => (
                    <option key={c.content_id} value={c.content_id}>{c.title || c.content_id}</option>
                  ))}
                </select>
              </label>

              <label>
                Algorithm
                <select value={algorithm} onChange={(e) => setAlgorithm(e.target.value)}>
                  <option value="linucb">LinUCB</option>
                  <option value="thompson">Thompson Sampling</option>
                </select>
              </label>

              <div className="actions">
                <button className="primary" onClick={handleRecommend}>Recommend artwork</button>
                <button onClick={() => handleFeedback(1.0)}>Submit click</button>
                <button onClick={() => handleFeedback(0.0)}>Submit no click</button>
                <button className="secondary" onClick={handleStats}>View stats</button>
              </div>
            </section>

            <section className="panel result-panel">
              <h2>Latest recommendation</h2>
              {result ? (
                <div className="card result-card">
                  <img src={result.artwork_image || ''} alt={result.artwork_id} />
                  <div className="card-body">
                    <h3>{result.artwork_id}</h3>
                    <p>Algorithm: {result.algorithm}</p>
                    <p>Impression ID: {result.impression_id}</p>
                    <p>Latency: {Math.round(result.latency_ms)} ms</p>
                  </div>
                </div>
              ) : (
                <p className="empty-state">No recommendation requested yet. Use the controls to generate your first prediction.</p>
              )}
            </section>
          </section>

          <section className="panel stats-panel">
            <h2>Live KPI dashboard</h2>
            {statsData ? (
              <div className="stats-grid">
                <div className="stat-card">
                  <span>Total impressions</span>
                  <strong>{statsData.total_impressions}</strong>
                </div>
                <div className="stat-card">
                  <span>Total clicks</span>
                  <strong>{statsData.total_clicks}</strong>
                </div>
                <div className="stat-card">
                  <span>Overall CTR</span>
                  <strong>{(statsData.overall_ctr * 100).toFixed(1)}%</strong>
                </div>
              </div>
            ) : (
              <p className="empty-state">Run the stats query to inspect production performance.</p>
            )}
          </section>
        </main>
      )}

      <footer>
        <p>{statusMsg || 'Ready'}</p>
        <small>Backend session auth is enabled when SSO credentials are configured.</small>
      </footer>
    </div>
  )
}